Next, to the your jurgency onboard a cruise ship tonight filled with hundreds of American passengers who suddenly became ill. The CDC rushing on board this Sunday. More than 300 sick. ABC's Reena ninan now. Reporter: Departing from new Jersey, a scare on the seas. 281 passengers and 22 crew members on a royal caribbean cruise fell ill, forcing the ship to alter its ten-day course, skipping a stop in Haiti and docking in San Juan, Puerto Rico. Passengers and crew members experiencing gastrointestinal illness. I caught it within the first 24 hours. The fever just kept going up and I realized when I couldn't keep a tablespoon of water down. Reporter: Today, health officials from the Senters of disease criminal boarding the ship to conduct an investigation. 90% of stomach illnesses on cruise ships are the result of a norovirus. A bug that effected the queen Mary 2 ship last year. The norovirus with be drought on board through contaminated water, food or infected passengers. The virus can spread quickly, because of the close living quarters, making it incredibly hard to contain. Health officials calling it a hardy virus. It can live on surfaces for days like doorknobs and handrails. It may take a couple more days before the CDC can confirm the cause of the illness. Cruise officials say they have, quote, taken a number of steps to prevent the transmission of the illness and sanitized the affected areas of the ship. For now, the cruise is expected to continue on to its final destination, to the island of St. Martin. Reena ninan, ABC news, New York.

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